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1983 Mercedes 300DT 301500 miles
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191 Posts
Discussion Starter #1
Hello everyone,
I just bought a 98 ml320 for $3100. It's cheap because it has issues. It runs but needs a one of everything. It has 195 000 miles. I know nothing about MLs. I have a w202 and a w123 which i do my own repairs. Never been to an actual shop.

The major thing that needs to be fixed before all the other issues is that when taking off from a complete stop if i don't accelerate extremely slowly it will make one or a few loud banging noises coming from underneath. Some times it sounds like it is coming from the front other times it sounds like it is coming from the back, but it could all be coming from the same spot I am not sure. It just sounds as if the drive shaft just bangs into something or as if something is skipping. As soon as I get it to go past 10-20mph it will not do it no matter how fast I go (i didn't try any faster then 50mph). And as long as it keeps rolling with more then 15mph it won't do it. It will do the same thing in reverse - if I accelerate extremely slow it will not do it but if I push on the gas a little more (which really is more like pushing it for normal driving not hard) it will bang.
I was told by the previous owner that it is the transfer case. I am not very convinced since the guy really didn't know what he is talking about and the car has not been maintained at all although he said he maintained it. For example the oil in the engine is so dirty that is probably more black then the oil in my diesel. Needless to say that I will be changing all the fluids, but i need to resolve this problem first.
I haven't gone under the car yet since I haven't had time and the weather is horrible, but I will try to look at it around christhmas.
The transmission shifts fine except that I did notice some slipping in some gears after it warmed up I am assuming it will defenatley need an oil change. And i will have to get a dipstick for it unless anybody knows how to modify one out of a 190E 722.4 transmission that I have laying in the shed.

I am taking any suggestions what to look for when I get a chance to go under the car.

thank you all.
 

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Outstanding Contributor - Always Remembered, RIP
Zotye Auto 1.5T T600 2016
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52,804 Posts
Center propshaft bearing most probably.
 

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Super Moderator
99 ML430, 00 ML320, 05 E500 4matic Wagon
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22,138 Posts
I am just guessing, but the bang you are getting is most likely due to collapsed engine
mounts. A very common issue. Also the trans mount. We had a ML in where the center
support drive shaft bearing was so worn it would clunk on take off.
 

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1990 190E 2.6,.... 1998 ML320, 2005 ML500SE
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3,103 Posts
My first guess would be the rear drive shaft center support bearing.

As for the transmission dipstick, make your own.
(Note: length is not that important since you insert the dipstick until it hits bottom and there will be several inches still sticking out of the dipstick tube)

Mike
(the pictures are from other Benzworld members -- thanks to them)
 

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ML270CDI Jan-2001
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11 Posts
My ML has exactly your described syntoms and is banging at least 5 times each foot down from stand still.
I am certain that the drive chain for the front axis in the Transfer Case is causing it. At high acceleration the chain jumps over the sprockets.
I will replace the chain as soon as I got one, hoping not to create too many metal fillings by then and save the sprockets.
 

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1983 Mercedes 300DT 301500 miles
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191 Posts
Discussion Starter #6 (Edited)
I had a chance to take a quick look underneath today. The drive shaft center support (behind the transfer case) is defenatly bad. I can grab the shaft and move it up and down and sideways about 1/10 of an inch of play.
Wouldn't that only cause vibrations though? I will be replacing it as soon as I can get the part but I am still thinking that there is something else more serious.
I didn't look at the mounts of the engine or transmission but will do that tomorrow.

What is that drive chain in the transfer case that "TamDee" is talking about? I read elsewhere in the forum about it too. Do you guys have a blown diagram of the transfer case? How do I check that chain?

I will see if the dipstick that I have out of a 190E 722.4 transmission is long enough to work with the ML with some modifications.

Thank you for the help guys. Merry christmas to everybody!

P.S. The ML has 20inch custom wheels, does that cause more load on the drivetrain?
Also I looked at all the axle boots and they seem to be in really good condition (I would almost say that they might have been replaced because they look like new). There didn't seem to be much leaks except from around the transmission which I think is leaking from the pan gasket and it seems to be only a little.
 

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1983 Mercedes 300DT 301500 miles
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191 Posts
Discussion Starter #7
By the way the local european junkyard has like 5 transfer cases from 99 ml430's with 79 to 150k miles for $400. Should I go buy one or should I replace the center support bearing first and change the oil in the transfer case and if it still doesn't work then go get one?
 

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2006 E350
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15 Posts
One thing I did was to put my finger on the large part of the rear half shafts (each one) in the rear, meanwhile my buddy put the car in DRIVE and held the brake hard. He then raised RMP and I could feel the poping from this area. Found out that my noise is the driver side Shaft in the rear...my car was doing the same thing you describe...just don't do it in reverse LOL...that might not be a good idea!
 

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1983 Mercedes 300DT 301500 miles
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191 Posts
Discussion Starter #9 (Edited)
One thing I did was to put my finger on the large part of the rear half shafts (each one) in the rear, meanwhile my buddy put the car in DRIVE and held the brake hard. He then raised RMP and I could feel the poping from this area. Found out that my noise is the driver side Shaft in the rear...my car was doing the same thing you describe...just don't do it in reverse LOL...that might not be a good idea!
I don't dare to do that. If I have my wife helping me she might just run me over:) I guess i will inspect it as good as I can when I remove the rear drive shaft in order to replace the support bearing. Are you saying that If I put on the brakes and have it in drive and push on the gas it will make that banging noise? I haven't tried that but I will.

I just tried that and while I hold on the brakes hard have it in drive and push on the gas when it gets to about 1500rpm or over that - it banged from the back then i let off the gas and did it again and it banged in the back again then i tried again this time it banged like 3-4 times in the front sounded kind of like a machine gun. I am thinking that it has to be that chain in the transfer case skipping since I just do not see why the driveshaft would make that noise. I think once it has torque on it there is nothing that can skip. I think that what is happaning is the chain is skipping and the torque is released from the drive-shaft for a moment and then reapplied and that's why it bangs.

I could put my camera under the car tomorrow and do this again and then post it on youtube.
 

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2006 E350
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LOL That would be cool...I want to dissasemble the rear half shaft as I think the splines may be worn to the point where thay cannot take a lot of torque...once the car is running the stress is much more reduced...not sure but thats my theory omn this elusive noise...I replaced the motor and trans mount...still does it.
I will be on the look out for your camera angle there...anyways I have a transfer case already in the garage just in case its that...just not sure that's what it is yet....but I could be mistaken....good luck...
 

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1983 Mercedes 300DT 301500 miles
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Discussion Starter #11 (Edited)
LOL That would be cool...I want to dissasemble the rear half shaft as I think the splines may be worn to the point where thay cannot take a lot of torque...once the car is running the stress is much more reduced...not sure but thats my theory omn this elusive noise...I replaced the motor and trans mount...still does it.
I will be on the look out for your camera angle there...anyways I have a transfer case already in the garage just in case its that...just not sure that's what it is yet....but I could be mistaken....good luck...
Well mine is making the noise from the front and the back. You are basically saying that the splines on the front of the rear drive shaft that go into the transfer case are bad and that in my case the splines that go into the front axle from the transfer case are also worn out and it skips there? I guess we will find out tomorrow as soon as I make that video.

By the way there is a video with a bad center support bearing:
Mine is not even half-way that bad. So that is defenatly not the problem
 

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ML270CDI Jan-2001
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11 Posts
Tedd300DT,
the inner of the Transfer Case is found here http://www.4x4abc.com/ML320/img/tx.jpeg
The chain is item 5 and the sprockets item 9.
In good old days MB has used proper gears to drive the front axis which last for a cars life time. Nowadays the cheaper chain option is common and apparently causing issues at high mileages as mine and yours are on.
I would not go for any used Transfer Case replacement unless you know it has low mileage or has been refurbished.
Check out this link for repair kits: Automatic, Standard Transmission and Transfer Case Rebuild Kits, Cobra Transmission Parts 1-800-293-1848.
I am hoping that BW4409 is the chain which will fit yours and mine as I havn't heard that the transfer cases from Borg Warner are different in ML's.
Off course we need to change the oil during the repair as I believe we have generated plenty of metall fillings with each machine gun shot and hopefully not caused any secondary damage in the other planetary gears.

Merry Christmas
 

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2006 E350
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15 Posts
TamDee...that makes a lot of sense. So basically the popping that I felt in the rear half shaft is actually something that is being transmitted to it from the "chain and gear" issue in the transfer case. I hope that makes sense....expressing things in writing may not be my strongest point. I have a trasnfer case that I bought used with 95K miles, my ML430 has 174,000. I guess now I need to look at steps to replace the trasnfer case (since I already have it) and go from there....I will keep this updated as I go along "the mystery of the strange popping noise from underneath" I like your term "machine gun"...LOL
 

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1983 Mercedes 300DT 301500 miles
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191 Posts
Discussion Starter #14
I made a short video of the noise:


also watch this one where a guy is working on a transfer case of a jeep with a stretched chain:
 

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1983 Mercedes 300DT 301500 miles
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191 Posts
Discussion Starter #15
Problem solved - I replaced the transfer case. By the way the noise in the video is nowhere near as loud as it actually sounds. The oil in the transfer case must have been the original oil with 196 500 miles. It really didn't look like oil it was really thick. There was no metal shavings in it. When the transfer case was on the ground i was turning it by hand and it was making a grinding sound compared to the replacement one which was not making such a sound. I did not replace the center support bearing because the parts haven't arrived yet and the support is really not in such a bad shape.
The replacement one is from a 99 ml430 with 78 000 miles and I paid $400 for it.
They have like 4 more left in that junkyard so if you guys need help finding a transfer case i can give you the website.

The moral of the story: "Change the oil at-least every 50k miles"

The transfer case that i got was not drained, but when i did drain it the oil was black but nowhere near as bad as the one from mine so I figure if the oil get's changed every 50k miles it would do fine.
I might open the old transfer case one day and see what happened, but it is obvious - lack of lubrication.

My next major problem is that the transmission is slipping I need to figure out why. It also has a leak from the connector and maybe the gasket. I will be changing the fluid soon. I am making me a dipstick right now so I can check the oil which I assume is low and assume the oil would be really nasty in it.
I might have to start a new thread on that.
 

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1990 190E 2.6,.... 1998 ML320, 2005 ML500SE
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Since you just purchased the vehicle I have a suspicion that the oil in the transfer case was changed. It was changed to a heavier weight oil to cover up the problem that existed when it was sold to you.
Mike
 

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1983 Mercedes 300DT 301500 miles
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191 Posts
Discussion Starter #17
Since you just purchased the vehicle I have a suspicion that the oil in the transfer case was changed. It was changed to a heavier weight oil to cover up the problem that existed when it was sold to you.
Mike
nope I bought it knowing about the problem (banging sound) and the previous owner said it is the transfer case but i had to investigate to make sure. The old transfer case had never been drained.
 

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99 ML 430; 61 220Sb
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55 Posts
Tedd,

how easy was it to replace the transfer case? I am about to do the same as you on an ML430. Do you have a DYI that you followed?

Also, what is the junkyard where you bought it from? I am in the search for one..
 
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